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logic

…Logic”) of the Italian Jesuit Gerolamo Saccheri. Saccheri is better known for his suggestion of the possibility of a non-Euclidean geometry in Euclides ab Omni Naevo Vindicatus (1733; “Euclid Cleared of Every Flaw”). Another incisive traditional logic was that of the Dutch philosopher Arnold Geulincx, Logica fundamentis suis restituta (1662;…

non-Euclidean geometry

In 1733 the Italian Girolamo Saccheri published his Euclides ab Omni Naevo Vindicatus (“Euclid Cleared of Every Flaw”). This was an important work of synthesis in which he provided a complete analysis of the problem of parallels in terms of Omar Khayyam’s quadrilateral (see the figure). Using the Euclidean…

In 1733 Girolamo Saccheri (1667–1733), a Jesuit professor of mathematics at the University of Pavia, Italy, substantially advanced the age-old discussion by setting forth the alternatives in great clarity and detail before declaring that he had “cleared Euclid of every defect” (Euclides ab Omni Naevo Vindicatus, 1733).…

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